Adult black flies, notably Simulium venustum and Prosimulium hirtipes, and mosquitoes of the Aedes, Anopheles and Culex genera are well known for their blood feeding habit. The feeding behavior involves puncturing the skin of the host, injecting a small quantity of anticoagulant, and ingesting blood. The reaction of the human host to the injection of the anticoagulant gives rise to swelling, redness and itching in the area immediately surrounding the bite.